Acoustics

Question 1

What are the 7 propulsion modes?

Answer 1

Turbo Reduction
Turbo Electric

Diesel Direct
Diesel Reduction
Diesel Electric

Battery Drive
Air Independant Propulsion

Question 2

What is the advantage of Nuclear Engine?

Answer 2

Range, speed and endurance

Question 3

What is the disadvantage of Nuclear

Answer 3

Constant noise sources

Question 4

Advantage of Diesel?

Answer 4

Very quiet on batteries

Question 5

Disadvantage of Diesel

Answer 5

Must snort to recharge batteries

Question 6

Define sound

Answer 6

Periodic variation of pressure, particle displacement or particle velocity in an elastic medium.

Question 7

Define a choke point

Answer 7

Geographical feature, above or below the surface of the sea, that restricts the freedom of movement of a submarine.

Question 8

Example of a choke point?

Answer 8

The English Channel

The Straits of Gibraltar

Greenland-Iceland-UK Gaps

Question 9

What are the three main requirements of a successful underwater detection system?

Answer 9

Good penetration (active) or sensitivity (passive)
High resolution
High data rate

Question 10

What three factors affect the speed of sound in water?

Answer 10

Temperature
Pressure
Salinity

Question 11

Which of the three factors that affect the speed of sound has the greatest effect?

Answer 11

Temperature

Question 12

Define the Doppler Phenomenon

Answer 12

Apparent change in frequency due to the relative motion between a source and receiver.

Question 13

What does DIFAR stand for?

Answer 13

Directional Frequency Analysis & Recording

Question 14

What are the selectable DIFAR Depths?

Answer 14

90, 200, 400, 1,000 ft

Question 15

What does DICASS stand for?

Answer 15

Directional Command Activated Sonobuoy System

Question 16

What is the DICASS operating life?

Answer 16

60 minutes (50 ping seconds)

Question 17

What information can be gained from a CPA?

Answer 17

Speed
Range
Bearing
Track
F0
Depth

Question 18

What does HALT stand for?

Answer 18

High Away, Low Towards

Question 19

What are the submarine types?

Answer 19

SSK Submersible Ship Killer
SSC Submersible Ship Coastal
SSP Submersible Ship Air Independant Propulsion
SSN Submersible Ship Nuclear
SSAN Submersible Ship Auxillary Nuclear
SSBN Submersible Ship Ballistic Missile Nuclear
SSGN Submersible Ship Guided Missile Nuclear

Question 20

What are the 2 types of seamounts that can be found in the ocean?

Answer 20

Pinnacles

Guyots

Question 21

Define Ambient Noise

Answer 21

Any noise within the ocean that is not target related.

Question 22

What are the two types of ambient noise?

Answer 22

Man-made and Natural

Question 23

What are the man-made sources of ambient noise?

Answer 23

Shipping noise
Seismic surveying
Drilling
Active transmissions

Question 24

What are the natural sources of ambient noise?

Answer 24

Biological
Ice
Weather
Seismic

Question 25

What are the main types of bottom composition?

Answer 25

Sand Rock Mud and Silt (Ooze)

Question 26

What are the 4 dimensions of a LOFARgram

Answer 26

Time Frequency Colour Intensity

Question 27

What propulsion modes are not common in submarines?

Answer 27

Diesel Direct | Diesel Reduction

Question 28

What equipment is involved in Snorting?

Answer 28

1st: Sonar underwater 2nd: ESM 3rd: Radar 4th: Periscope 5th: Snort induction mast

Question 29

Reasons to surface?

Answer 29

Battery Charging Communications Attack solutions Emergency

Question 30

What is the difference between active and passive sonar?

Answer 30

Active two way transmission | Passive one way transmission

Question 31

What is the effect of ambient noise?

Answer 31

The lower the amount of ambient noise, the greater the range of detection.

Question 32

What is the definition of frequency?

Answer 32

number of complete waves cycles passing a fixed point in 1 second, measured in Hz

Question 33

How does temperature affect the speed of sound in water?

Answer 33

1 degree Celsius increase = increase by 3m/s

Question 34

How does pressure affect the speed of sound in water?

Answer 34

100m increase in depth = increase by 2m/s

Question 35

How does salinity affect the speed of sound in water?

Answer 35

Increase of 1 part per thousand = increase by 1.1 m/s

Question 36

What are the three types of Sonobuoys?

Answer 36

SSQ-53F DIFAR SSQ-62E DICASS SSQ-36B Expendable Bathythermograph

Question 37

What is the operating life of a DIFAR?

Answer 37

05, 1, 2, 4, or 8 hours

Question 38

What is the operating depth of a DICASS?

Answer 38

D1 (Shallow): 50, 150, or 300ft | D2 (Deep): 90, 400, or 1500ft

Question 39

What is the life of a Bathy?

Answer 39

12 minutes

Question 40

What is the operating depth of a Bathy?

Answer 40

2625ft

Question 41

Three layer ocean model?

Answer 41

``` Temperature going across Depth doing down Mixed layer (straight line) Thermocline (line angled to left) Deep water (straight line) ```

Question 42

Ocean topography model?

Answer 42

``` Shelf Slope Rise Abyssal Plain Deep Trench Seamount/ridge Abyssal Plain ```

Question 43

What is BR?

Answer 43

Blade Rate - the no. of times the blades pass a given point 'A' in 1 second, measured in Hz

Question 44

What is SR?

Answer 44

Shaft Rate - the no. of times a propeller shaft rotates in one second.

Question 45

What is fundamental frequency?

Answer 45

The base or origin frequency measured in cycles per second and expressed in Hz

Question 46

What is Harmonic Frequency?

Answer 46

An echo or numerous echos of the fundamental frequency throughout the spectrum.

Question 47

What is SRPM?

Answer 47

Shaft revolutions per minute.

Question 48

What is CSR?

Answer 48

Crank Shaft Rate - the no. of times the crankshaft rotates in one second

Question 49

What is CFR?

Answer 49

Cylinder Firing Rate - the no. of times an individual cylinder fires in one second

Question 50

What is EFR?

Answer 50

Engine Firing Rate - the no. of times the engine fires in one second

Question 51

What is ERPM?

Answer 51

Engine Revolutions Per Minute - the number of times the crankshaft rotates in on minute

Question 52

Diesel Electric diagram?

Answer 52

Diesel Engine -> Generator -> Batteries -> Motor -> Propeller

Question 53

Primary Coolant Loop in a Turbo Reduction?

Answer 53

Pressurizer Steam Generator Reactor Main Coolant Pump

Question 54

Secondary Coolant Loop in a Turbine Reduction Engine

Answer 54

Turbo Generator, Main Turbine, Electrical Propulsion Motor Motor Generator, SSTG, Clutch, Reduction Gearing AC/DC, Main Condensor, Battery

Question 55

Formula for F0

Answer 55

(Fmax + Fmin)/2

Question 56

Formula for Speed?

Answer 56

Speed = [(Fmax-Fmin)/F0] x AV In kts

Question 57

Formula for Range

Answer 57

Range = speed x time x 17 In yards